Internet traffic varies according to at least two scales: first, because of the emergence of new applications and the increasing number of Internet users, internet traffic increases exponentially when considered over long time periods (e.g., yearly) and, second, fluctuations in usage on smaller time scales (e.g., daily) occur. When upgrading networks, carriers provide for significantly higher bandwidth than needed to support expected traffic growth over the course of years. However, before each upgrade, carriers also require spectrum or bandwidth savings to ensure that the network will be able to operate into the future. Energy efficiency is also desirable to reduce operational costs, which in the case of power consumption will be roughly proportional to the traffic volume.
Recent technologies have improved the bandwidth efficiency of optical networks. Such technologies include optical signal to noise ratio (OSNR) adaptive modulation and Nyquist rate transponders as well as band switching in optical switches. Higher modulation formats also increase energy efficiency by reducing the symbol rate. However, these technologies are generally available only on static configurations. Whenever the network configuration—such as modulation format or symbol rate—needs to be changed, the connectivity will be temporarily interrupted and the customer will experience loss of data. Traffic-adaptive transport configuration is believed to reduce overall power consumption and to increase global network resource utilization, but the lack of hitless service provisioning prohibits the realization of these advantages.